Dukes Fuel Pump

[Flybrian1950]

I found an earlier post on this website indicating an ex maule engineer who will remain un named had a source for the "bearing" seal that is the common leak source on these pumps.
I was able to acquire one of the bearing units, about $80, had a capable set of airframe mechanic hands follow the installation guidance and affect a reseal. I have had 5 years or trouble free flying on the re-sealed unit.
Since they are only rated for 5 minutes of continuous use, I test mine at startup, shut it off and forget it.
I hope this procedure gives me a better chance, If it is going to fail, of finding out on the ground during taxi, instead of in the air when I change tanks and might need it.

I would be great if Maule provided a legal alternative to replace the Dukes with one of the Facet pumps used in the auto fuel conversion for the 540 B4B5 and the 360 C1F/4F.

Seems like Maule Flight could do this as an STC, and make it an option for those who will still be using 100LL, but want better pump reliability. They could just sell the paperwork, and everyone could buy the pump at AC Spruce. Oh what a dream on a foggy Saturday!

[taildragger]

Hi,

I have an M5 210/C with the Continental IO 360. My Dukes fuel boost pump is leaking bad. It is the original according to the logs. ( old vanes, etc ) The pump I pulled off is a 4140-00-57. Is the only option the fleecing of $1250 for O/H or is there a Weldon or similar replacement option for less? Thanks.

Scott

[TimB]

That works sometimes but the drive pin and slotted shaft between the motor and pump wears and causes an out of round vibration witch takes out the bearing and seal assembly that you just replaced and requires motor replacement to solve the real problem

[taildragger]

I am foolishly assuming that for $1250 the o/h on a Dukes includes a new motor? I guess what I am hoping for is if it possible to put a Weldon 1800 new for $725 or some other similar pump on as a replacement for less. The Weldon ( I hate to say it here lol ) works on "Cessna's" with the same engine. Thanks.

Scott

[vern]

There is a Weldon fuel pump on my '73 M4-210C. It was there when I acquired the project in 2008.

[iceman]

Ok i had mine overhauled by dukes a couple years ago for around 600 bucks. Cant immagine they ovr doubled that

[MauleMechanic]

I have opened up and replaced the brass part with o-rings on the outside and inside of the brass part. Assuming the new veins have already been installed, most leaks are due to running the pump dry and damaging the o-rings. Simply replacing the brass with o-rings part will solve the problem, or it has many times for my customers leaks. The veins can only be installed one way, there is a slight curve on one end of each vein and can easily be installed incorrectly and normally fall out when dis-assembling the parts. I can pull one apart while still mounted on the airplane with a few tricks. If you can even find the part for sale, replacing it can be a pain for the novice tinkerer.

If I have time, I will try to open up and old pump and take some photos but it can be seen in the manual posted somewhere in the previous replies. I think it was part #4 but do not remember the actual part number.

[Green Hornet]

I had a good experience with this approach. http://maulepilots.org/forums/viewtopic ... ight=dukes

[yanknbank]

There has been a couple mentions of the main shaft seal part being possible to acquire. I dunno why all the secrecy, but does anyone have info on where one can get their hands on this seal without having to go full overhaul?

[Kirk]

I believe I will have a used one available in a month or two. Being removed as part of the autofuel stc.

Don’t have the logs at my location, so can’t provide time in service since overhaul. It is in working condition with no leaks.

Kirk

[yanknbank]

Thanks Kirk. I think I'll be needing one much sooner by the looks of it. Don't think I'll be trying to make it back to home base with it leaking like it is.

[Kirk]

Bummer to be grounded but a prudent decision.

Fuel leaks = bad. Fuel leaks forward of the firewall = very bad.

Think I read that in some tech publication. Hope you can get it fixed.

Kirk

[yanknbank]

I got a pump exchanged at aeromotors. I broke down in Madison Wisconsin, and turns out they were an hour drive away. Great guys, and quick to help. They were able to find a core and build it for me before I got there. If they didn't have one, they were willing to build mine and let me watch.

All their parts are machined in house. They are basically the same as the dukes pump in concept, but a lot more care goes into balancing the rotor so as not to create any excessive drag, which will lead to an it off round wearing, and subsequent leaking. They advised me that while they rebuild Waldon pumps too, they don't like them, and think they are inferior to a rebuilt dukes due to a square drive that wears easier, thus causing early wear of the shaft seal. They thought the cj pumps were a mess too, and refuse to rebuild them.

I think maule got the wrong pump pressure for a continental io-360, and so do they, but that's what I got, so I'll live with it. Just seems a 7psi pump isn't going to help much on a motor that needs 17psi on the event of an engine driven pump malfunction, but maybe I'm wrong. Hope not to find out.

I recommend aeromotors over the alternatives.

[norcal64d]

I used Aeromotors when my Duke pump seized up and they were awesome. Its been working great ever since, but since talking to Maule, I only use the pump on a takeoff where I suspect vapor lock could be an issue such as a takeoff after the plane shutdown recently in warmer weather.